host: process table, shell, coreutils and harness (T8, T9)

T8: sausage:process WIT (spawn, wait, kill), one store per process over the
shared root, /proc/processes, /run, pipeline and cancellation groups, Exec.
brush and 78 uutils commands; the shared cwd-init object sets the cwd from PWD
and keeps numeric exit codes. The corpus matches native bash.

T9: V8 (deno_core) runs pi-durable, pi-ai and chord; SQLite storage in
<dir>/host/harness.sqlite (WAL, synchronous=FULL); file tools on the VFS, bash
through Exec; resumes after SIGKILL.

userland/procps/src/main.rs

@@ -0,0 +1,31 @@
+//! ps reads the process snapshot. kill stops a process group through the process interface.
+mod bindings {
+    wit_bindgen::generate!({ path: "../../host/wit", world: "program", generate_all });
+}
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    match std::path::Path::new(&args[0])
+        .file_name()
+        .unwrap()
+        .to_str()
+        .unwrap()
+    {
+        "ps" => print!(
+            "{}",
+            std::fs::read_to_string("/proc/processes").expect("process snapshot")
+        ),
+        "kill" => {
+            if args.len() < 2 {
+                std::process::exit(2);
+            }
+            for pid in &args[1..] {
+                let pid: u32 = pid.parse().expect("numeric pid");
+                if let Err(error) = bindings::sausage::process::host::kill(pid) {
+                    eprintln!("kill: {error}");
+                    std::process::exit(1);
+                }
+            }
+        }
+        _ => std::process::exit(127),
+    }
+}